Purified surface fimbriae from Actinomyces viscosus strain T14V may be effective for inducing salivary antibodies that interfere with the adsorption of this human periodontopathogen to tooth surfaces, thereby interfering with colonization and subsequent disease. Accurate assessment of the role of fimbriae-specific salivary antibody in the inhibition of bacterial adsorption requires not only a sensitive quantitative assay, but also a revelant functional assay. The combination of the quantitative assay with the functional assay allows correlation of the relative amount of fimbriae-specific antibody to the adsorption inhibition activity of the antibody. Furthermore, an in vitro functional assay would be useful for determining immunization protocols in animal models that stimulate a fimbriae-specific salivary antibody response effective in the inhibition of bacterial adsorption not only to hydroxyapatite surfaces in vitro, but also to tooth surfaces in vivo. The information obtained from effective immunization protocols in animal models indentified by the in vitro functional assay may be applicable to the immunoprotection of humans against periodontal diseases.